Amphibians/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim and Moby are at a pond. Moby holds a salamander by the tail. TIM: Hey, put him down. How would you like it if someone picked you up by your tail? Moby, still holding the salamander, looks back to see if he has a tail. MOBY: Beep. TIM: Oh, you know what I mean. Tim reads from a typed letter. TIM: Dear Tim and Moby, what are amphibians? From, Leigh. Amphibians are vertebrate, or backbone-bearing, animals like frogs, salamanders, and newts. An image shows salamanders, frogs, and a caecilian. TIM: Their ancestors were the first vertebrates to venture onto land about 370 million years ago. An animation shows an amphibian from prehistoric times crawling out of the water onto land. TIM: Existing amphibians are split into three groups. An digram shows how the amphibian family tree is split into three types. TIM: Anurans, or frogs and toads, have short bodies, strong legs; and no tails. An image shows a frog and toad. TIM: Urodeles have long bodies, short legs, and flattened tails for swimming. An image shows salamanders and a newt. TIM: Organisms in the group Apoda are called caecilians. These guys are practically blind worm-like creatures that look a lot like snakes. An image shows a caecilian which looks like a giant worm or snake. TIM: Most amphibians split their lives between land and water in a similar way. They're born in the water, stick to the land as adults, and return to the water to breed. An animation shows a frog born in the water, living on land, and laying eggs in the water. MOBY: Beep. TIM: Well, many amphibians undergo a metamorphosis that lets them move from a water life to a land life. Take frogs. An animation shows a frog. TIM: A frog starts out as a fertilized egg cell in the water. The egg develops into a tadpole that lives in the water and breathes using gills. As the tadpole matures, it grows legs, and its body shape changes. An animation shows a frog's life starting as an egg in water, turning into a tadpole, and the tadpole transforming into a frog. TIM: When metamorphosis is complete, the frog has a set of lungs that allows it to breathe outside of the water. Strong back legs help it to move on land, and big eyes and a long tongue help it spot and catch prey. An animation shows a mature frog sitting on a lily pad. Its long tongue catches and eats a fly. MOBY: Beep. TIM: Amphibians are ectothermic, or cold-blooded. That means they depend on their surroundings to establish their body temperature. An image shows a frog with two thermometers. One thermometer reads, frog temperature 76° F, the other reads outside temperature 55° F. The frog's temperature changes to 55 degrees Fahrenheit. TIM: In extreme hot and extreme cold weather amphibians sometimes go through a period of reduced metabolic activity called torpor. It's a little bit like hibernation. A split image shows both a frog and salamander with most of their bodies buried in the ground. MOBY: Beep. TIM: Yeah, I always thought it would be fun to slow down and just sleep. Moby lies down in a hole in the ground. TIM: Hey, what are you doing down there? MOBY: Beep. TIM: What? I'm not going to pour water on you. Category:BrainPOP Transcripts